ir skin. Normally it is very soft, but, for example, in response to a threat, the animal can activate its 'body armor' by hardening its skin," explains Capadona, who has a sea cucumber in his aquarium. Marine biologists have shown in earlier studies that the switching effect in the biological tissue is derived from a distinct nanocomposite structure in which highly rigid collagen nanofibers are embedded in a soft connective tissue. The stiffness is mediated by specific chemicals that are secreted by the animal's nervous system and which control the interactions among the collagen nanofibers. When connected, the nanofibers form a reinforcing network which increases the overall stiffness of the material considerably, when compared to the disconnected (soft) state.
Building on their recent success on the fabrication of artificial polymer nanocomposites containing rigid cellulose nanofibers, which earned them the December 2007 cover of Nature Nanotechnology, the team mimicked the architecture nature 'designed' for the sea cucumbers and created artificial materials that display similar mechanical morphing characteristics.
The Case Western Reserve/VA team is specifically interested in using such dynamic mechanical materials in biomedical applications, for example as adaptive substrates for intracortical microelectrodes. These devices are being developed as part of 'artificial nervous systems' that have the potential to help treat patients that suffer from medical conditions such as Parkinson's disease, stroke or spinal cord injuries, i.e., disorders in which the body's interface to the brain is compromised. A problem observed in experimental studies is that the quality of the brain signals recorded by such microelectrodes usually degrades within a few months after implantation, making chronic applications challenging. One hypothesis for this failure is that the high stiffness of these electrodes, which is required for their insertion, causes damage to the surroundPage: 1 2 3 Related biology technology :1
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